An investigation was made of the use of O from H2O2 in the National Carbon air cell and of the effect of elevated temperature and increased electrolyte concentration on the performance of this cell. Theoretical aspects of this problem were considered. The construction of the CGS500 air cell is discussed and the voltage-measurement and current-measurement and cell-loading circuits are described. The cell consisting of the electrode assembly and approximately 4 1 of electrolyte in a 4-1 beaker was placed on an electric hot plate. Readings were taken as the cell was heated and as it cooled. The following data were obtained: (1) open-circuit voltage of the cell, (2) open-circuit voltage of referenc e vs O electrode, (3) current drawn from the cell, (4) cell Zn vs O voltage for these currents, (5) reference Zn vs O voltage for these currents, and (6) temperature of the cell. Test results indicated that operation at high temperatures was superior to room-temperature operation. High- temperature operation reduced polarization and internal resistance of a cell utilizing an O electrode. The use of highly concentrated electrolyte also reduced polarization. There was an optimum electrolyte concentration for minimum internal cell resistance for a givenoperating temperature. It was concluded that the use of concentrated electrolyte and operation at elevated temperature can result in increased capacity of the O electrode.